Changeset 90599 in webkit

Timestamp:

Jul 7, 2011, 4:16:19 PM (15 years ago)

Author:

commit-queue@webkit.org

Message:

Work around Skia PDF's lack of inverted path support.
​https://bugs.webkit.org/show_bug.cgi?id=64032

Patch by Steve VanDeBogart <​vandebo@chromium.org> on 2011-07-07
Reviewed by James Robinson.

The trick used in ​http://neugierig.org/software/chromium/notes/2010/07/clipping.html
to support antialiased clips doesn't work when printing to Skia's PDF backend because
the backend does not support inverted paths. This manifests as rounded buttons not being
drawn when printing, tracked as Chrome bug 79519.

However, when the output is a vector device, like PDF, we don't need antialiased clips.
It's up to the PDF rendering engine to do that. So we can simply disable the antialiased
clip code if the output is a vector device.

I think the fix isn't testable because it requires examining the printed output.

• platform/graphics/skia/PlatformContextSkia.cpp:

(WebCore::PlatformContextSkia::clipPathAntiAliased):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/skia/PlatformContextSkia.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-07-07  Steve VanDeBogart  <vandebo@chromium.org>
+
+        Work around Skia PDF's lack of inverted path support.
+        https://bugs.webkit.org/show_bug.cgi?id=64032
+
+        Reviewed by James Robinson.
+
+        The trick used in http://neugierig.org/software/chromium/notes/2010/07/clipping.html
+        to support antialiased clips doesn't work when printing to Skia's PDF backend because
+        the backend does not support inverted paths. This manifests as rounded buttons not being
+        drawn when printing, tracked as Chrome bug 79519.
+        
+        However, when the output is a vector device, like PDF, we don't need antialiased clips.
+        It's up to the PDF rendering engine to do that.  So we can simply disable the antialiased
+        clip code if the output is a vector device.
+        
+        I think the fix isn't testable because it requires examining the printed output.
+
+        * platform/graphics/skia/PlatformContextSkia.cpp:
+        (WebCore::PlatformContextSkia::clipPathAntiAliased):
+
 2011-07-07  Emil A Eklund  <eae@chromium.org>
 

trunk/Source/WebCore/platform/graphics/skia/PlatformContextSkia.cpp

@@ -297 +297 @@
 void PlatformContextSkia::clipPathAntiAliased(const SkPath& clipPath)
 {
+    if (m_canvas->getTopDevice()->getDeviceCapabilities() & SkDevice::kVector_Capability) {
+        // When the output is a vector device, like PDF, we don't need antialiased clips.
+        // It's up to the PDF rendering engine to do that. We can simply disable the
+        // antialiased clip code if the output is a vector device.
+        canvas()->clipPath(clipPath);
+        return;
+    }
+
     // If we are currently tracking any anti-alias clip paths, then we already
     // have a layer in place and don't need to add another.